This invention relates to link and media access layer transaction initiation procedures in a communication system, and more particularly, to such procedures in time slotted communication systems.
Link layer recovery protocols are used for error and loss recovery in data communication systems. Link layer recovery is especially crucial for wireless communications due to the particularly harsh loss and error characteristics of the link.
Typically, a link layer recovery protocol is initialized at the time of connection establishment. Also, in the case of data link protocols for cellular communications, the radio link protocol (RLP) is not implemented at the base station but typically situated back in the network so that data flows across the connection seamlessly as the mobile traverses multiple cells (across multiple handoffs). When a connection is established, the network typically assigns a unique temporary identifier which may be associated with a data link connection to a specific mobile station. For example in Cellular Digital Packet Service (CDPD), the Mobile Data link Protocol (MDLP) is established at packet data registration, and a Temporary Equipment Identifier (TEI) is assigned to the mobile station. The TEI is used by peer data link layer entities for subsequent data transfer.
Packet data transactions tend to be bursty with possibly long periods of inactivity between transactions. For mobile stations involved in intermittent transactions, with long inter-transaction times (even though each transaction may involve significant data transfer), maintaining RLP back in the network has the following disadvantages: maintaining the RLP state information across long idle periods is a very inefficient use of network resources; moving the RLP back into the network has an adverse impact on performance due to increased round trip delay; moving the RLP back into the network makes it harder to use adaptive modulation and incremental redundancy schemes, that can have a significant throughput advantage; maintaining a unique identifier across long idle periods is very inefficient and requires the use of a large identifier field (for example the TEI in CDPD); and using the identifiers in each Medium Access control (MAC) layer transmission is desirable to avoid ambiguity, but long identifiers are wasteful of RF bandwidth.
In a TDMA Digital Control Channel (DCCH), a 7 bit Partial Echo (PE) field has been used as a mobile station identifier. However, for users with intermittent packet transactions, there is significant probability of ambiguity with 7 bit PEs.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.
In accordance with the present invention, there is provided a system and method of implementing a radio link protocol and dynamic partial echo management for a transaction oriented packet data communication system. The method performs the steps of determining a data backlog with a media access control layer controller and transmitting a PDU to a receiver. The method further performs the step of initiating a media access control layer transaction in response to the transmitting of the BEGIN PDU.
Also in accordance with the present invention, a system for implementing a radio link protocol (RLP) and dynamic partial echo management for a transaction oriented packet data system. The system comprises a media access control layer controller for determining a data backlog in a media access control layer buffer and a media access control layer transmitter for transmitting a BEGIN Protocol Data Unit to a receiver. The system also includes a means for initiating a media access control layer transaction in response to the transmitting of the BEGIN Protocol Data Unit.
These and other features and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings and the appended claims.